We thought it would at the time, but then Beta 4 changed the ABI
again, so it wasn't true in practice.

Fixes #17643

Change-Id: I36b747bd69a56adc7291fa30d6bffdf67ab8741b
Reviewed-on: https://go-review.googlesource.com/32238Reviewed-by: Russ Cox <rsc@golang.org>